Totally, in business critical systems for all sorts of stuff.

Rewriting it would be enormous effort and provide no business benefit and be full or risk of introducing new (or re-introducing old) bugs in the process of converting to some whiz-bang c# or whatever is trendy.

We even built custom integration modules (DLLs in Visual C++ 6 for anyone curious). They integrate to legacy AS/400 systems and the interfaces used are totally legacy and unlikely to be easy to integrate with c++ 2015.

So, we're absolutely still using Tcl (and Tk) in 2015 and it is still relevant. It will be in use until the company (or the sun) implodes.

I do hate the syntax though. Yuk. [edit: I see others commenting that that's the thing they like ! I'm obviously an outlier or our code sucks more than most.]